It is often necessary to obtain a sample of a body fluid and perform an analysis of an analyte in that body fluid. Preferably, the obtaining of body fluid is as painless as possible, and the collection of the sample is as simple as possible. One example of a need to obtain a sample of a body fluid is in connection with a blood glucose monitoring system where a user must frequently use the system to monitor the user's blood glucose level.
Those who have irregular blood glucose concentration levels are medically required to regularly self-monitor their blood glucose concentration level. An irregular blood glucose level can be brought on by a variety of reasons including illness such as diabetes. The purpose of monitoring the blood glucose concentration level is to determine the blood glucose concentration level and then to take corrective action, based upon whether the level is too high or too low, to bring the level back within a normal range. The failure to take corrective action can have serious implications. When blood glucose levels drop too low—a condition known as hypoglycemia—a person can become nervous, shaky, and confused. That person's judgment may become impaired and that person may eventually pass out. A person can also become very ill if his blood glucose level becomes too high—a condition known as hyperglycemia. Both conditions, hypoglycemia and hyperglycemia, are both potentially life-threatening emergencies.
One method of monitoring a person's blood glucose level is with a portable, hand-held blood glucose testing device. The portable nature of these devices enables the users to conveniently test their blood glucose levels wherever they may be. To check the blood glucose level, a drop of blood is obtained from the fingertip using a separate lancing device. The lancing device contains a needle lance to puncture the skin. Once the requisite amount of blood is produced on the fingertip, the blood is harvested using the blood glucose testing device. The blood is drawn inside the testing device, which then determines the concentration of glucose in the blood. The results of the test are communicated to the user via a display on the testing device.
One problem related with the prior art devices containing a separate lance and sample collection mechanism is that the user must carry both devices with him. The need to carry multiple devices opens the possibility of forgetting or losing one of the devices. If the user forgets to bring both the lance and the testing device with him, he will not be able to test his blood; adverse consequences may result.
Another problem with a monitoring system comprising a lancing device to lance the skin and a separate collection unit to collect the blood is that there is a greater chance of contaminating the sample. The user must be careful that he does not contaminate the blood drop that forms on the lance site or contaminate the collection device used. If any contamination occurs, the test result may not accurately reflect the level of the glucose present in the tested blood.
A third problem with having a device for lancing and a separate device for collection is the size of the sample needed. Users prefer to make smaller cuts, also referred to as lance sites, on their skin to produce a blood sample. A smaller lance site is usually less painful to make than a larger lance site, and should heal more quickly than a larger lance site. Generally, a smaller lance site will produce a smaller blood sample. The smaller the sample, the more important proper collection of the sample becomes. And a smaller sample requires greater precision in placing the collection device relative to the lance site. If the collection device is not properly positioned relative to the lance site on the user's skin, the requisite amount of sample may not be collected. If the requisite amount of sample is not collected an underfill condition occurs. The results of analyzing an underfill will not accurately reflect the amount of glucose present in the sample, or in the user.
Another problem with current lancing devices is that accidental lancing may occur from the exposed lance. If the lance is exposed it may come into contact with the user's skin in a location that the user did not intend to serve as a lance site. This cut may be painful and limit the available locations for a lance site.
Accordingly, there exists the need of a device that combines lancing capability and collection capability into one instrument. The combination device should be suitable for lancing skin and aligning the collection device at the lance site, collecting a small sample of blood from a small lance site on the skin, and reducing risk of accidental lance sites being formed from an exposed lance.